Segmentation fault on de-referencing int field over 3 levels
Frank Benoit (keinfarbton)
benoit at tionex.removethispart.de
Fri Feb 23 02:15:43 PST 2007
the Date is a struct and is of value type. (1) is OK so.
The MyDate is a class and is a reference type. This is why (2) fails.
You did not initialize Author.birth.
> public class Author {
> public:
> MyDate birth;
this(){
birth=new MyDate();
}
> };
Oliver Moeller schrieb:
> Compiling the following with DMD and executing the program
> yields an segmentation fault when accessing the public field
> 'the_date.year' of another public field 'birth':
>
>
> import std.c.stdio;
> import std.c.stdlib;
> import std.string;
> import std.date;
>
> public class MyDate {
> public:
> Date the_date; // only the field 'year' is relevant
>
> this(){ the_date.year = 1901; }
> };
>
> public class Author {
> public:
> MyDate birth;
> };
>
> int main(char[][] args)
> {
> Author author = new Author();
> MyDate mydate = new MyDate();
>
> printf("(1) accessing: mydate.the_date.year = %i\n", mydate.the_date.year);
> printf("(2) accessing: author.birth.the_date.year = \n");
> printf("%i\n", author.birth.the_date.year);
>
> printf("Ok.\n");
>
> return 0;
> }
>
> To my understanding, this access is legal; if not, then the compiler should
> refuse it.
> Enlighten me if I am doing something wrong here (I am new to D).
>
> Here is the screen output sniplet: -------------------------------------
> phobos:~/Lang/D/Toy/segfault> make test
> /home/oli/Projects/D/DMD/dmd/bin/dmd -c -oftest_date.o test_date.d
> /home/oli/Projects/D/DMD/dmd/bin/dmd -oftest_date.exe test_date.o
> gcc test_date.o -o test_date.exe -m32 -lphobos -lpthread -lm
>
> phobos:~/Lang/D/Toy/segfault> ./test_date.exe
> (1) accessing: mydate.the_date.year = 1901
> (2) accessing: author.birth.the_date.year =
> Segmentation fault
> -------------------------------------------------------------------------
> Running test_date.d interpreted has the same effect (abort on (2)).
>
> Versions:
> dmd: Digital Mars D Compiler v1.0
> gcc: gcc (GCC) 4.0.2 20050901 (prerelease) (SUSE Linux)
> platform: PC SuSE Linux 10.0 (64 bit)
>
> ** Computers will always make mistakes, but will do so much faster tomorrow.
> ** ------------------------------------------------- <omoeller at verify-it.de>
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